Amyotrophic lateral sclerosis (ALS): The Daily PANCE Blueprint
A 62-year-old woman presents with a 9-month history of worsening slurred speech, difficulty swallowing, and hand clumsiness. Examination reveals fasciculations in her tongue and brisk reflexes in her extremities. Which of the following diagnostic tests would be most helpful in confirming a diagnosis of ALS?
A. Electromyography (EMG) and nerve conduction studies
B. Complete blood count (CBC) and erythrocyte sedimentation rate (ESR)
C. Magnetic resonance imaging (MRI) of the brain
D. Lumbar puncture for cerebrospinal fluid (CSF) analysis
E. Muscle biopsy
Answer and topic summary
The answer is A. Electromyography (EMG) and nerve conduction studies
Electromyography (EMG) and nerve conduction studies are crucial in the diagnosis of ALS, as they can detect abnormalities in muscle and nerve function that are characteristic of the disease. EMG can reveal signs of denervation and reinnervation in muscles, even those not clinically affected, helping to differentiate ALS from other neuromuscular disorders.
- B. Complete blood count (CBC) and erythrocyte sedimentation rate (ESR): These tests are nonspecific and are typically used to rule out other conditions, not to diagnose ALS.
- C. Magnetic resonance imaging (MRI) of the brain: While MRI can help rule out other causes of the patient’s symptoms, such as spinal cord lesions or brain tumors, it cannot diagnose ALS directly.
- D. Lumbar puncture for cerebrospinal fluid (CSF) analysis: CSF analysis can be normal in ALS or show mild protein elevation, but it is not diagnostic of the disease.
- E. Muscle biopsy: Rarely used in the diagnosis of ALS and typically reserved for cases where the diagnosis is unclear after comprehensive testing.
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